Field of the Invention
The present invention relates generally to the use of vault compositions as adjuvants for stimulating a cellular immune response to one or more antigens, for example, tumor antigens or cancer biomarkers. Also included in the invention is the use of the compositions for the treatment of diseases, such as cancer.
Introduction
With ongoing disease threats and the promise of emerging immunotherapies, demand for new vaccine technologies is growing. Developing effective and potent vaccines remains one of the most cost-effective strategies for preventing infectious diseases and cancers [1,2]. Vaccines containing killed or inactivated intact microbes elicit strong immune responses but also produce considerable inflammation at the site of vaccination [3-5]. Furthermore, engineered live vaccines, such as non-replicating recombinant viruses have been developed and also induce robust immune responses [6-8]. However, the potential for break-through replication of live vectors and anti-vector immunity further discourage the development of live vector vaccines due to safety concerns [9,10]. To further vaccine development, non-replicating adjuvants are needed which induce robust immunity with minimal inflammation.
The immune-promoting activity of any given vaccination strategy is determined by the presence of the relevant antigenic components in the vaccine formulation, enhanced by the addition of suitable adjuvants capable of activating and promoting an efficient immune response against infectious agents or cancers [1,2]. One approach for tailoring vaccines to elicit certain types of immune responses while avoiding inflammation is to develop subunit vaccines by combining non-living or synthetic antigens with adjuvants [9]. This type of vaccine can deliver defined antigens with reduced inflammatory cytokine production but is dependent on the adjuvant formulation to stimulate cell-mediated immune responses and protection from infectious challenge or prevent tumor growth [11,12]. Most licensed vaccines promote immunity by eliciting humoral immune responses and weak cellular immune responses. Current efforts are directed to producing adjuvants which elicit cell-mediated immunity [13,14].
A major limiting factor in the development of subunit vaccines is engineering immune adjuvants to induce cell-mediated immunity and encourage CD8− T cell responses through major histocompatibility complex (MHC) class I presentation (MHC-I, cross presentation). Previous work has shown that it is difficult to achieve antigen presentation through MHC-I molecules unless the antigen is specifically targeted to the MHC-I processing machinery [15-17]. A wide range of approaches has been explored including CpG-DNA or toll-like receptor (TLR) ligands, recombinant viral vectors, fusion with bacterial toxins and others [18,19]. Adjuvants can also be designed to elicit specific immunity, such as promoting cellular immunity which is important for protection against many pathogens [20]. Currently none have been successfully developed for use in humans.
Nanoparticle pharmaceutical carriers can be engineered to elicit various types of immunity and are increasingly investigated as adjuvants for vaccines. Different types of nanocarriers, such as polymers (polymeric nanoparticles, micelles, or dendrimers), lipids (liposomes), viruses (viral nanoparticles), and organometallic compounds (carbon nanotubes) have been employed for immunotherapeutic applications [21-23]. We have engineered vaults using a recombinant technique to function as a nanocarrier. Natural vaults are barrel-shaped, hollow, 13 mDa ribonucleoprotein particles that exist in nearly all eukaryotic cells [24,25]. Their precise function is unknown but they have been associated with multidrug resistance, cell signaling, nuclear-cytoplasmic transport and innate immunity [26]. We have shown that recombinant vaults can be produced to contain a bacterial antigen and induce adaptive immune responses and protective immunity following immunization [27]. In addition, vault nanocapsules can also be engineered to promote anti-tumor responses [28]. These studies show that recombinant vault nanocapsules act as adjuvants, are versatile for eliciting various types of immunity and have outstanding potential for compound encapsulation, protection, and delivery.
Description of the Related Art
Vaults are cytoplasmic ubiquitous ribonucleoprotein particles first described in 1986 that are found in all eukaryotic cells (Kedersha et al., J Cell Biol, 103(3):699-709 (1986)). Native vaults are 12.9±1 MDa ovoid spheres with overall dimensions of approximately 40 nm in width and 70 nm in length (Kong et al., Structure, 7(4):371-379 (1999); Kedersha et al., J Cell Biol, 112(2):225-235 (1991)), present in nearly all-eukaryotic organisms with between 104 and 107 particles per cell (Suprenant, Biochemistry, 41(49):14447-14454 (2002)). Despite their cellular abundance, vault function remains elusive although they have been linked to many cellular processes, including the innate immune response, multidrug resistance in cancer cells, multifaceted signaling pathways, and intracellular transport (Berger et al., Cell Mol Life Sci, 66(1):43-61 (2009)).
Vaults are highly stable structures in vitro, and a number of studies indicate that the particles are non-immunogenic (Champion et al., PLoS One, 4(4):e5409 (2009)). Vaults can be engineered and expressed using a baculovirus expression system and heterologous proteins can be encapsulated inside of these recombinant particles using a protein-targeting domain termed INT for vault INTeraction. Several heterologous proteins have been fused to the INT domain (e.g. fluorescent and enzymatic proteins) and these fusion proteins are expressed in the recombinant vaults and retain their native characteristics, thus conferring new properties onto these vaults (Stephen et al., J Biol Chem, 276(26):23217-23220 (2001); Kickhoefer et al., Proc Natl Acad Sci USA, 102(12):4348-4352 (2005)).
Vaults are generally described in U.S. Pat. No. 7,482,319, filed on Mar. 10, 2004; U.S. application Ser. No. 12/252,200, filed on Oct. 15, 2008; International Application No. PCT/US2004/007434, filed on Mar. 10, 2004; U.S. Provisional Application No. 60/453,800, filed on Mar. 20, 2003; U.S. Pat. No. 6,156,879, filed on Jun. 3, 1998; U.S. Pat. No. 6,555,347, filed on Jun. 28, 2000; U.S. Pat. No. 6,110,740, filed on Mar. 26, 1999; International Application No. PCT/US1999/06683, filed on Mar. 26, 1999; U.S. Provisional App. No. 60/079,634, filed on Mar. 27, 1998; and International Application No. PCT/US1998/011348, filed on Jun. 3, 1998. Vault compositions for immunization against chlamydia genital infection are described in U.S. application Ser. No. 12/467,255, filed on May 15, 2009. The entire contents of these applications are incorporated by reference in their entirety for all purposes.